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🐍 PyPI
Not in CISA KEV
HIGH severity

CVE-2013-1895 — py-bcrypt

HIGH

CVE-2013-1895 is a high-severity (CVSS 7.5) CWE-307 vulnerability in py-bcrypt. A fix is available for py-bcrypt — see the affected versions and patch details below.

Improper Restriction of Excessive Authentication Attempts in py-bcrypt

Also known asGHSA-r838-q6jp-58xxPYSEC-2020-249
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
2.8%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs86th percentile — riskier than 86% of all scored CVEsHighest risk
0.68%1.56%2.45%3.33%1.2%1.2%2.8%2.8%2.8%May 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2013-1895 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐍py-bcrypt

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

The py-bcrypt module before 0.3 for Python does not properly handle concurrent memory access, which allows attackers to bypass authentication via multiple authentication requests, which trigger the password hash to be overwritten.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIpy-bcryptall versions0.3pip install --upgrade 'py-bcrypt==0.3'

Affected Products

2 products · 3 configurations
OS
fedorafedoraproject
2 versions
1718
Application
py-bcryptpython
< 0.3
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for py-bcrypt, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update py-bcrypt to 0.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2013-1895 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

The py-bcrypt module before 0.3 for Python does not properly handle concurrent memory access, which allows attackers to bypass authentication via multiple authentication requests, which trigger the password hash to be overwritten.
O3 Security · Impact-Aware SCA

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CVE-2013-1895: py-bcrypt — Fixed in 0.3